In order to attract the youngster's attention, inventors have designed many products in their market, such as scooters, tricycles, baby strollers, toy cars, roller skates, skateboards, shopping carts, bicycles . . . etc., many of which comprise illumination devices. However, the illumination devices require electric power to work. Most of the power uses the wheel rotation to generate power. When the wheel rotates, electric power is generated to activate the illumination devices. If the wheel rolls slow, the electric power is week and the illuminating effect is affected.